Procedure for stabilising polyunsaturated fatty acids with metal hydrides

Abstract

The invention relates to a procedure for stabilising polyunsaturated fatty acids with selective reducing agents. In particular, the invention relates to a process of preparation of polyunsaturated acids of the omega-3 series, as such or in the form of esters, which comprises treatment of fish oil or a mixture of acids with urea, and subsequent treatment with a metal hydride, preferably sodium borohydride. The polyunsaturated fatty acids of greatest interest present in fish oil are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

1 . A process for the preparation of omega-3 polyunsaturated fatty acids or the esters thereof, in isolated form or in a mixture, from oils or mixtures containing them, which process comprises selectively enriching by precipitation urea adducts in the presence of reducing agents. 
     
     
         2 . A process according to  claim 1 , wherein the polyunsaturated fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the corresponding ethyl esters. 
     
     
         3 . A process according to  claim 1 , wherein mixtures of omega-3 polyunsaturated acids having an 80% minimum content of EPA and DHA ethyl esters, with a minimum of 40% EPA ethyl esters and a minimum of 34% DHA ethyl esters, and a 90% minimum content of ethyl esters of omega-3 acids, are obtained. 
     
     
         4 . A process according to  claim 1 , wherein the reducing agent is sodium borohydride. 
     
     
         5 . A process according to  claim 4 , wherein sodium borohydride is used in amounts ranging from 0.1 to 20% by weight of the total mixture or oil to be treated. 
     
     
         6 . A process according to  claim 5 , wherein sodium borohydride is added in a solid form. 
     
     
         7 . A process according to  claim 4 , wherein hydride treatment is carried out at a temperature ranging from 0° to 50° C. or, when using a solvent and fish oil as starting material, at a temperature ranging from 0° to 100° C. 
     
     
         8 . A process according to  claim 4 , wherein crystallization by means of urea is carried out in methanol or ethanol, while cooling the mixture to a temperature of 0°-25° C. in a time ranging from about 1 to 8 hours. 
     
     
         9 . A process according to  claim 8 , wherein the crystallization is carried out in methanol and ethanol mixed together and/or with water.